Pub I've played in Maidenhead expects 10pm-1am with two breaks (3 sets).
You tend to get different audiences for each set, as people move up and down the high street, get thrown out of closing pubs, etc. Obviously the last set is when the alcohol starts to really take a hold…so we save the rockier/best numbers till then.
Last time we played there, we packed up at 12.30 unexpectedly. Our lead singer's daughter had been taken to hospital, and he'd found out at 9, so we played through a break and finished early. Trouble was, no-one bothered to tell me! But kudos to him for sticking with it (she was okay).